Thinking further on the gears

I revisited the mechanism and started calculating..
Also I left out four smaller gears for two larger ones, this will decrease the amount of drag from the gears.
Since three red gears have to move as one and there positioning is crucial, I had to calculate the sizes and positions of the connecting gears exactly. Also I found it esthetically pleasing to have the neck-bob at about half the standard gear speed.
The ratios had to be determined, so that the number of 'teeth' on each gear would be an integer, else the gears cannot connect.
After two hours or so I came up with 4 standard gears of 40 teeth all having the same speed (the red ones and the yellow one). 
A gear (purple) scaled 240% giving 96 teeth, with a speed of 41.667% of the standard for the neck.
A gear (cyan) scaled 325% giving 130 teeth (and a speed of about 30%), connecting the standard gear with the neck gear.
A gear (fuchsia) scaled 275% with 110 teeth (and a speed of 36.4%) connecting the two aft standard gears.

This is math at it's finest. You can actually create something in advance, and know it will work perfectly. Just to be sure, I simulated the gears in flash and found something out.
I'll have to revise my scetch of the body shape (background, grey) a little bit, because some of the gears were sticking out.

in this detail of the standard gear stuck between the two oversized ones, you can see how needly everything fitted and why I felt like da Vinci for working it out in advance.. (Or maybe Hannibal from the A-team, saying: "I love it when a plan comes together!")